מוסר אויף נחמיה 13:2

Concerning the above mentioned matters, the Torah wrote in Deut. 30,1: "It will be when all these things befall you, the blessing and the curse that I have set before you, and you take them to heart amidst the various nations to which the Lord your G–d has banished you, and you return to the Lord your G–d, etc." Why did the Torah see fit to mention הברכה, "the blessing," in that verse? All that needed to be mentioned is the curse which eventually would lead to repentance! We therefore see, that the Torah wanted to make the point that the curse itself is really a dimension of the blessing. This is parallel to the verse in Nechemiah 13,2: ויהפוך אלוקינו הקללה לברכה"" Our G–d turned the curse into a blessing." Bileam, who had come prepared to curse, was forced to bless instead. The angel who delights in evil was forced to give his consent to the blessings; the accuser was turned into an advocate for the defense.